wp-config.php changes itself once a day

Hello!

There’s a problem with my WordPress –
Everything is fine, site is working. But then at night, at about 1am CET, the wp-config.php is updating itself.
The related lines are:

/** MySQL database username */
define(‘DB_USER’, ‘name1’);

and

/** MySQL hostname */
define(‘DB_HOST’, ‘localhost’);

in the first line it constantly changes from “name1” to “name2”.
in the second line it constantly changes from “localhost” to “localhost:3306”.

I’m really out of ideas. Is there any chance anyone knows why this problem exists?